[PATCH 5/7] i2c: qcom-geni: Add support for GPI DMA

[Vinod Koul <vkoul@kernel.org>]

This adds capability to use GSI DMA for I2C transfers

Signed-off-by: Vinod Koul <vkoul@kernel.org>
---
 drivers/i2c/busses/i2c-qcom-geni.c | 246 ++++++++++++++++++++++++++++-
 1 file changed, 244 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
index 046d241183c5..6978480fb4d1 100644
--- a/drivers/i2c/busses/i2c-qcom-geni.c
+++ b/drivers/i2c/busses/i2c-qcom-geni.c
@@ -12,7 +12,9 @@
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/dmaengine.h>
 #include <linux/qcom-geni-se.h>
+#include <linux/dma/qcom-gpi-dma.h>
 #include <linux/spinlock.h>
 
 #define SE_I2C_TX_TRANS_LEN		0x26c
@@ -48,6 +50,8 @@
 #define LOW_COUNTER_SHFT	10
 #define CYCLE_COUNTER_MSK	GENMASK(9, 0)
 
+#define I2C_PACK_EN		(BIT(0) | BIT(1))
+
 enum geni_i2c_err_code {
 	GP_IRQ0,
 	NACK,
@@ -72,6 +76,12 @@ enum geni_i2c_err_code {
 #define XFER_TIMEOUT		HZ
 #define RST_TIMEOUT		HZ
 
+enum i2c_se_mode {
+	UNINITIALIZED,
+	FIFO_SE_DMA,
+	GSI_ONLY,
+};
+
 struct geni_i2c_dev {
 	struct geni_se se;
 	u32 tx_wm;
@@ -86,6 +96,17 @@ struct geni_i2c_dev {
 	u32 clk_freq_out;
 	const struct geni_i2c_clk_fld *clk_fld;
 	int suspended;
+	struct dma_chan *tx_c;
+	struct dma_chan *rx_c;
+	dma_cookie_t rx_cookie, tx_cookie;
+	dma_addr_t tx_ph;
+	dma_addr_t rx_ph;
+	int cfg_sent;
+	struct dma_async_tx_descriptor *tx_desc;
+	struct dma_async_tx_descriptor *rx_desc;
+	enum i2c_se_mode se_mode;
+	bool cmd_done;
+	bool is_shared;
 };
 
 struct geni_i2c_err_log {
@@ -429,6 +450,183 @@ static int geni_i2c_tx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
 	return gi2c->err;
 }
 
+static void i2c_gsi_cb_result(void *cb, const struct dmaengine_result *result)
+{
+	struct geni_i2c_dev *gi2c = cb;
+
+	if (result->result != DMA_TRANS_NOERROR) {
+		dev_err(gi2c->se.dev, "DMA txn failed:%d\n", result->result);
+		return;
+	}
+
+	if (result->residue)
+		dev_dbg(gi2c->se.dev, "DMA xfer has pending: %d\n", result->residue);
+
+	complete(&gi2c->done);
+}
+
+static int geni_i2c_gsi_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
+			     int num)
+{
+	struct geni_i2c_dev *gi2c = i2c_get_adapdata(adap);
+	struct dma_slave_config config;
+	struct gpi_i2c_config peripheral;
+	int i, ret = 0, timeout = 0;
+
+	memset(&config, 0, sizeof(config));
+	memset(&peripheral, 0, sizeof(peripheral));
+	config.peripheral_config = &peripheral;
+	config.peripheral_size = sizeof(peripheral);
+
+	if (!gi2c->tx_c) {
+		gi2c->tx_c = dma_request_slave_channel(gi2c->se.dev, "tx");
+		if (!gi2c->tx_c) {
+			dev_err(gi2c->se.dev, "tx dma_request_slave_channel fail\n");
+			ret = -EIO;
+			goto geni_i2c_gsi_xfer_out;
+		}
+	}
+
+	if (!gi2c->rx_c) {
+		gi2c->rx_c = dma_request_slave_channel(gi2c->se.dev, "rx");
+		if (!gi2c->rx_c) {
+			dev_err(gi2c->se.dev, "rx dma_request_slave_channel fail\n");
+			ret = -EIO;
+			goto geni_i2c_gsi_xfer_out;
+		}
+	}
+
+	if (!gi2c->cfg_sent) {
+		const struct geni_i2c_clk_fld *itr = gi2c->clk_fld;
+
+		peripheral.pack_enable = I2C_PACK_EN;
+		peripheral.cycle_count = itr->t_cycle_cnt;
+		peripheral.high_count = itr->t_high_cnt;
+		peripheral.low_count = itr->t_low_cnt;
+		peripheral.clk_div = itr->clk_div;
+		gi2c->cfg_sent = true;
+		peripheral.set_config =  true;
+	}
+
+	peripheral.multi_msg = false;
+	for (i = 0; i < num; i++) {
+		struct device *rx_dev = gi2c->se.wrapper->dev;
+		struct device *tx_dev = gi2c->se.wrapper->dev;
+		int stretch = (i < (num - 1));
+		u8 *dma_buf = NULL;
+		unsigned int flags;
+
+		gi2c->cur = &msgs[i];
+
+		peripheral.addr = msgs[i].addr;
+		peripheral.stretch = stretch;
+		if (msgs[i].flags & I2C_M_RD)
+			peripheral.op = I2C_READ;
+		else
+			peripheral.op = I2C_WRITE;
+
+		dma_buf = i2c_get_dma_safe_msg_buf(&msgs[i], 1);
+		if (!dma_buf) {
+			ret = -ENOMEM;
+			goto geni_i2c_gsi_xfer_out;
+		}
+
+		if (msgs[i].flags & I2C_M_RD) {
+			gi2c->rx_ph = dma_map_single(rx_dev, dma_buf,
+						     msgs[i].len, DMA_FROM_DEVICE);
+			if (dma_mapping_error(rx_dev, gi2c->rx_ph)) {
+				dev_err(gi2c->se.dev, "dma_map_single for rx failed :%d\n", ret);
+				i2c_put_dma_safe_msg_buf(dma_buf, &msgs[i], false);
+				goto geni_i2c_gsi_xfer_out;
+			}
+
+			peripheral.op = I2C_READ;
+			peripheral.stretch = stretch;
+			ret = dmaengine_slave_config(gi2c->rx_c, &config);
+			if (ret) {
+				dev_err(gi2c->se.dev, "rx dma config error:%d\n", ret);
+				goto geni_i2c_gsi_xfer_out;
+			}
+			peripheral.set_config =  false;
+			peripheral.multi_msg = true;
+			peripheral.rx_len = msgs[i].len;
+
+			flags = DMA_PREP_INTERRUPT | DMA_CTRL_ACK;
+			gi2c->rx_desc = dmaengine_prep_slave_single(gi2c->rx_c, gi2c->rx_ph,
+								    msgs[i].len,
+								    DMA_DEV_TO_MEM, flags);
+			if (!gi2c->rx_desc) {
+				dev_err(gi2c->se.dev, "prep_slave_sg for rx failed\n");
+				gi2c->err = -EIO;
+				goto geni_i2c_err_prep_sg;
+			}
+
+			gi2c->rx_desc->callback_result = i2c_gsi_cb_result;
+			gi2c->rx_desc->callback_param = gi2c;
+
+			/* Issue RX */
+			gi2c->rx_cookie = dmaengine_submit(gi2c->rx_desc);
+			dma_async_issue_pending(gi2c->rx_c);
+		}
+
+		dev_dbg(gi2c->se.dev, "msg[%d].len:%d W\n", i, gi2c->cur->len);
+		gi2c->tx_ph = dma_map_single(tx_dev, dma_buf, msgs[i].len, DMA_TO_DEVICE);
+		if (dma_mapping_error(tx_dev, gi2c->tx_ph)) {
+			dev_err(gi2c->se.dev, "dma_map_single for tx failed :%d\n", ret);
+			i2c_put_dma_safe_msg_buf(dma_buf, &msgs[i], false);
+			goto geni_i2c_gsi_xfer_out;
+		}
+
+		peripheral.stretch = stretch;
+		peripheral.op = I2C_WRITE;
+		ret = dmaengine_slave_config(gi2c->tx_c, &config);
+		if (ret) {
+			dev_err(gi2c->se.dev, "tx dma config error:%d\n", ret);
+			goto geni_i2c_gsi_xfer_out;
+		}
+		peripheral.set_config =  false;
+		peripheral.multi_msg = true;
+		gi2c->tx_desc = dmaengine_prep_slave_single(gi2c->tx_c, gi2c->tx_ph, msgs[i].len,
+							    DMA_MEM_TO_DEV,
+							    (DMA_PREP_INTERRUPT |  DMA_CTRL_ACK));
+		if (!gi2c->tx_desc) {
+			dev_err(gi2c->se.dev, "prep_slave_sg for tx failed\n");
+			gi2c->err = -ENOMEM;
+			goto geni_i2c_err_prep_sg;
+		}
+		gi2c->tx_desc->callback_result = i2c_gsi_cb_result;
+		gi2c->tx_desc->callback_param = gi2c;
+
+		/* Issue TX */
+		gi2c->tx_cookie = dmaengine_submit(gi2c->tx_desc);
+		dma_async_issue_pending(gi2c->tx_c);
+
+		timeout = wait_for_completion_timeout(&gi2c->done, XFER_TIMEOUT);
+		if (!timeout) {
+			dev_err(gi2c->se.dev, "I2C timeout gsi flags:%d addr:0x%x\n",
+				gi2c->cur->flags, gi2c->cur->addr);
+			gi2c->err = -ETIMEDOUT;
+		}
+geni_i2c_err_prep_sg:
+		if (gi2c->err) {
+			dmaengine_terminate_all(gi2c->tx_c);
+			gi2c->cfg_sent = 0;
+		}
+		if (msgs[i].flags & I2C_M_RD)
+			dma_unmap_single(rx_dev, gi2c->rx_ph, msgs[i].len, DMA_FROM_DEVICE);
+		else
+			dma_unmap_single(tx_dev, gi2c->tx_ph, msgs[i].len, DMA_TO_DEVICE);
+		i2c_put_dma_safe_msg_buf(dma_buf, &msgs[i], !gi2c->err);
+		if (gi2c->err)
+			goto geni_i2c_gsi_xfer_out;
+	}
+
+geni_i2c_gsi_xfer_out:
+	if (!ret && gi2c->err)
+		ret = gi2c->err;
+	return ret;
+}
+
 static int geni_i2c_xfer(struct i2c_adapter *adap,
 			 struct i2c_msg msgs[],
 			 int num)
@@ -448,6 +646,15 @@ static int geni_i2c_xfer(struct i2c_adapter *adap,
 	}
 
 	qcom_geni_i2c_conf(gi2c);
+
+	if (gi2c->se_mode == GSI_ONLY) {
+		ret = geni_i2c_gsi_xfer(adap, msgs, num);
+		goto geni_i2c_txn_ret;
+	} else {
+		/* Don't set shared flag in non-GSI mode */
+		gi2c->is_shared = false;
+	}
+
 	for (i = 0; i < num; i++) {
 		u32 m_param = i < (num - 1) ? STOP_STRETCH : 0;
 
@@ -462,6 +669,7 @@ static int geni_i2c_xfer(struct i2c_adapter *adap,
 		if (ret)
 			break;
 	}
+geni_i2c_txn_ret:
 	if (ret == 0)
 		ret = num;
 
@@ -628,7 +836,8 @@ static int __maybe_unused geni_i2c_runtime_suspend(struct device *dev)
 	int ret;
 	struct geni_i2c_dev *gi2c = dev_get_drvdata(dev);
 
-	disable_irq(gi2c->irq);
+	if (gi2c->se_mode == FIFO_SE_DMA)
+		disable_irq(gi2c->irq);
 	ret = geni_se_resources_off(&gi2c->se);
 	if (ret) {
 		enable_irq(gi2c->irq);
@@ -653,8 +862,41 @@ static int __maybe_unused geni_i2c_runtime_resume(struct device *dev)
 	ret = geni_se_resources_on(&gi2c->se);
 	if (ret)
 		return ret;
+	if (gi2c->se_mode == UNINITIALIZED) {
+		int proto = geni_se_read_proto(&gi2c->se);
+		u32 se_mode;
+
+		if (unlikely(proto != GENI_SE_I2C)) {
+			dev_err(gi2c->se.dev, "Invalid proto %d\n", proto);
+			geni_se_resources_off(&gi2c->se);
+			return -ENXIO;
+		}
+
+		se_mode = readl_relaxed(gi2c->se.base + GENI_IF_DISABLE_RO) &
+				FIFO_IF_DISABLE;
+		if (se_mode) {
+			gi2c->se_mode = GSI_ONLY;
+			geni_se_select_mode(&gi2c->se, GENI_GPI_DMA);
+			dev_dbg(gi2c->se.dev, "i2c GSI mode\n");
+		} else {
+			int gi2c_tx_depth = geni_se_get_tx_fifo_depth(&gi2c->se);
+
+			gi2c->se_mode = FIFO_SE_DMA;
+			gi2c->tx_wm = gi2c_tx_depth - 1;
+			geni_se_init(&gi2c->se, gi2c->tx_wm, gi2c_tx_depth);
+			geni_se_config_packing(&gi2c->se, BITS_PER_BYTE,
+					       PACKING_BYTES_PW, true, true, true);
+			qcom_geni_i2c_conf(gi2c);
+			dev_dbg(gi2c->se.dev,
+				"i2c fifo/se-dma mode. fifo depth:%d\n", gi2c_tx_depth);
+		}
+		dev_dbg(gi2c->se.dev, "i2c-%d: %s\n",
+			gi2c->adap.nr, dev_name(gi2c->se.dev));
+	}
+
+	if (gi2c->se_mode == FIFO_SE_DMA)
+		enable_irq(gi2c->irq);
 
-	enable_irq(gi2c->irq);
 	gi2c->suspended = 0;
 	return 0;
 }
-- 
2.26.2